[Go]redis Server and client keepalive parameters (tcp-keepalive) settings

Recently, using the Redis list for cross-process Message Queuing, clients are using Redis-cplusplus-client. This client library is fine, and it's handy to have a consistent interface with redis command line.

The following problem was found during use.

I have multiple clients connecting to the same database, and the client Blpop data from Redis, setting the timeout to 5 seconds. Ordinarily there is no problem, the client is not many, there is no pressure on the database. But after running for a while, the client will not get data from Redis.

The first thing to think about is whether the database connection is broken. View the 6379-port TCP connection from both the Redis and client sides, and find that the connection to the client is not true. But the client was no exception, still in that silly blpop! It seems that this third-party library is still not well done.

One solution is to not maintain a long connection between client and Redis, and each operation is reconnected. feasible, but too simple.

Later, I looked at the Redis configuration file and found a tcp-keepalive option.

# TCP KeepAlive.
#
# If Non-zero, use so_keepalive to send TCP ACKs to clients in absence
# of communication. This was useful for the reasons:
#
# 1) Detect dead peers.
# 2) Take the connection alive from the point of view of the network
# Equipment in the middle.
#
# on Linux, the specified value (in seconds) are the period used to send ACKs.
# Note that to close the connection, the double of the time is needed.
# on and kernels the period depends on the kernel configuration.
#
# A Reasonable value for this option is seconds.
Tcp-keepalive 0

It is used to periodically send tcp_ack packets to the client to detect if the client is alive. Default does not detect, the official recommended value is 60 seconds. Then try it.

This setting, after observing a period of time, discovers that the connection between the client and the Redis is maintained. Work!

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[Go]redis Server and client keepalive parameters (tcp-keepalive) settings